脳内におけるカテコーラミン含有顆粒

On the Catecholamine-containing Granules in the Brain

I．緒言

　1963年6月脳研連主催のシンポジアム「行動の神経機構」で著者が「脳の組織化学（光顕的および電顕的）」について講演した時，視床下部吻側部の内側核に神経分泌物と異なるいわゆるgranular（granulated）vesicles（含粒小胞）（GV）がneuropilにおいて，シナプス末端，それに近い軸索内に見られ，末梢交感神経におけるanalogy，よりおそらくノルアドレナリン（NA）を含むものであろうと報告した（清水）^24）。しかしこの報告後著者らの所見とまつたく同様の成績がすでにde Iraldiら^4）によつて1963年4月号のAnatomical Recordに発表されていることを知つた。我々は脳内におけるこの特殊顆粒について引き続き主として電顕的に研究を続け2,3の知見を加えることができたので報告する。

　観察部は多数の先人による生化学的成績および組織化学的所見よりカテコーラミン含量が大で，その代謝が旺盛と思われる部を主とした。

1) In the various portions of the brain of rats andrabbits we studied the distribution of granular vesiclesprobably containing catecholamines by electron-microscope. The granular vesicles were mostnumerous in the anterior and ventro-medial hypo-thalamic nuclei, and less abundant in the subepen-dymal tissue and lateral hypothalamic nucleus.Moderate numbers of granular vesicles were demon-strated in the area postrema and supraoptic crest.In the striatum little if any granular vesicles couldbe seen, while in the pallidum as well as in theformatio reticularis of the pons many granularvesicles were demonstrable. The granular vesicleswere located in the synaptic terminals and preter-minal axons of the neuropil, while they were veryfew in number in the perikaryons except for thosein the area postrema and formatio reticularis. Inthe synaptic endings they were located at somedistance from the synaptic membrane and inter-mingled with synaptic vesicles. Glycogen particleswere usually found in the astrocytes surroundingthe synaptic contacts.

2) With the intention of identifying the contentof granular vesicles, the electron microscopicobservation was accompanied by the biochemicaldetermination of catecholamines after injection ofreleasers. Following intraperitoneal injection ofreserpine (10 mg/Kg) the number of granularvesicles was counted on the electronmicrographs ofthe anterior hypothalamic nucleus and area postrema.Three to four hours after injection the granularvesicles markedly decreased in number in thehypothalamus (less than one half of the control),no appreciable changes occurring in the area post-rema. After injection of Win 18501-2 (70 mg/Kg) the content of noradrenaline and dopamine wasdetermined in the medial and lateral parts of thehypothalamus and in the area postrema and com-pared with the number of granular vesicles in the corresponding areas. Win produced prominent and parallel decrease in the content of noradrenaline and the number of granular vesicles in the medial part of the hypothalamus. In the area postrema normal high content of noradrenaline did not change in accordance with unaltered number of granularvesicles. Dopamine content did not show any rela-tion with granular vesicles in both the control andWin-injected animals.

3) Distribution of monoamine oxidase andacetylcholinesterase was studied in relation togranular vesicles. We tried the application ofGlenner's method to the electron microscopic leveland observed the activity of monoamine oxidaseto be localized in the particles resembling lysosomein the perikaryon and mitochondria-like particlesin the neuropil. Acetylcholinesterase was studiedaccording to Torack and Barrnett with slight modi-fication. The activity occurred as dense particulatedeposits within the large vacuoles related to the Golgicomplex and on the endoplasmic reticulum of theperikaryon. In the neuropil the activity of acetyl-cholinesterase was demonstrable within the axon terminrls and dendritic branches, and on the pre-and postsynaptic membranes. In the hypothalamus we observed slight but definite activity in the axon terminals which contained both granular and synaptic vesicles.